////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1996-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#if ! defined (octave_oct_env_h)
#define octave_oct_env_h 1

#include "octave-config.h"

#include <string>

namespace octave
{
  namespace sys
  {
    class
    OCTAVE_API
    env
    {
    protected:

      env (void);

    public:

      // No copying!

      env (const env&) = delete;

      env& operator = (const env&) = delete;

      static std::string polite_directory_format (const std::string& name);

      static bool absolute_pathname (const std::string& s);

      static bool rooted_relative_pathname (const std::string& s);

      static std::string base_pathname (const std::string& s);

      static std::string
      make_absolute (const std::string& s,
                     const std::string& dot_path = get_current_directory ());

      static std::string get_current_directory (void);

      static std::string get_home_directory (void);

      static std::string get_temp_directory (void);

      static std::string get_user_config_directory (void);

      static std::string get_user_data_directory (void);

      static std::string get_program_name (void);

      static std::string get_program_invocation_name (void);

      static std::string get_user_name (void);

      static std::string get_host_name (void);

      static std::string getenv (const std::string& name);

      static void putenv (const std::string& name, const std::string& value);

      static bool have_x11_display (void);

      static bool chdir (const std::string& newdir);

      static void set_program_name (const std::string& s);

    private:

      static bool instance_ok (void);

      std::string do_polite_directory_format (const std::string& name) const;

      bool do_absolute_pathname (const std::string& s) const;

      bool do_rooted_relative_pathname (const std::string& s) const;

      std::string do_base_pathname (const std::string& s) const;

      std::string do_make_absolute (const std::string& s,
                                    const std::string& dot_path) const;

      std::string do_getcwd (void) const;

      std::string do_get_home_directory (void) const;

      std::string do_get_temp_directory (void) const;

      std::string do_get_user_config_directory (void) const;

      std::string do_get_user_data_directory (void) const;

      std::string do_get_user_name (void) const;

      std::string do_get_host_name (void) const;

      std::string do_getenv (const std::string& name) const;

      void do_putenv (const std::string& name, const std::string& value) const;

      bool do_chdir (const std::string& newdir);

      void do_set_program_name (const std::string& s) const;

      void pathname_backup (std::string& path, int n) const;

      void error (int) const;

      void error (const std::string&) const;

      // The real thing.
      static env *m_instance;

      static void cleanup_instance (void)
      { delete m_instance; m_instance = nullptr; }

      // TRUE means follow symbolic links that point to directories just
      // as if they are real directories.
      bool m_follow_symbolic_links;

      // TRUE means that pwd always give verbatim directory, regardless
      // of symbolic link following.
      bool m_verbatim_pwd;

      // Where are we?
      mutable std::string m_current_directory;

      // Etc.
      mutable std::string m_prog_name;

      mutable std::string m_prog_invocation_name;

      mutable std::string m_user_name;

      mutable std::string m_host_name;
    };
  }
}

#endif
